Disk type recording devices, whether magnetic, magnetoresistive or magnetooptical types, are high precision devices requiring the precise location and support of parts which interact in the positioning of a transducer head for recording or reading purposes. The recording devices are fabricated in a clean environment or cleaned prior to assembly in a clean environment and require a clean environment in which to function. Disk type recording devices such as memory devices comprise at least one disk on which servo code and/or digital data is recorded in concentric or spiral tracks. At least one transducer mounted on a moveable actuator is moved to a selected radial position to access selected data, which in a disk memory drive is usually at the request of a host computer.
The recorded tracks are bounded by tracks at inner and outer radial positions on a disk surface. Actuator movement is limited by limit stops or crash stops, which limit transducer displacement to inner and outer radial positions, at least radially inwardly and radially outwardly of the radial positions of those inner and outer tracks upon which data is recorded. The function of these crash stops is to absorb the impact energy of the actuator thereagainst and to stop the actuator in the shortest possible distance without exceeding the acceleration force limits of the transducers and the transducer supports in the designed operational environment.
To prevent damage due to shock forces, disk drives are provided with actuator restraining devices or locks which secure the actuator in one of two radial limits of movement, inner or outer, to prevent uncontrolled actuator movement when the disk drive is not in use, the object being to avoid dragging the transducers in contact with the disk surface across the tracks. Typically, this locked position places the transducers in a radial zone outside of the recorded tracks reserved for parking, taking off, and loading, so as to eliminate transducer sliding over recorded tracks and damaging the data, and/or recording surface.
These actuator locks, by way of example, operate according to various technical principles including, magnetic, electromagnetic, mechanical, aerodynamic, and combinations thereof.
U.S. Pat. Nos. 4,538,193 and 4,647,997 describe actuator locks having latches which are spring biased to latched position and which are aerodynamically released. U.S. Pat. No. 4,692,829 describes an actuator having a latch which is magnetically repelled to latch position and aerodynamically released. U.S. Pat. No. 5,036,416 describes an actuator having a latch which is magnetically attracted or spring loaded to latched position and which is aerodynamically released.
These latches while functionally effective in locking and unlocking the actuator, involve numerous parts which add to the complexity of the drive, to the inventory costs, to the assembly costs, and finally to the maintenance costs. Reliability in real life applications is suspect. Such added complexity increases the power consumption of the spindle motor.